Remove unused rule as GtkButton:inner-border has been deprecated
Remove unused rule as GtkButton:inner-border has been deprecated

See documentation:
http://developer.gnome.org/gtk3/stable/GtkButton.html#GtkButton--s-inner-border

Upstream bug opened by Benjamin:
https://bugzilla.gnome.org/show_bug.cgi?id=485762

Signed-off-by: Manuel Quiñones <6f5069c5b6be23302a13accec56587944be09079@laptop.org>

sugarlabs/sugar-artwork,godiard/sugar-artwork,godiard/sugar-artwork,samdroid-apps/sugar-artwork,godiard/sugar-artwork,samdroid-apps/sugar-artwork,i5o/sugar-artwork,samdroid-apps/sugar-artwork,i5o/sugar-artwork,tchx84/debian-pkg-sugar-artwork,sugarlabs/sugar-artwork,tchx84/debian-pkg-sugar-artwork,sugarlabs/sugar-artwork,tchx84/debian-pkg-sugar-artwork,i5o/sugar-artwork